1. Field of the Invention
This invention relates to ink jet printer apparatus and in particular to ink jet printer method and apparatus in which both magnetic and electrostatic deflection of the ink stream are employed.
2. Description of the Prior Art
Ink jet printing methods and apparatus are generally well known and comprise the projection of a continuous stream of ink droplets toward a record medium, such as a sheet of paper. Deflection of the drops in a given direction, plus relative motion of the medium and/or deflection in a direction orthogonal to the first direction, will produce a dot matrix pattern on the record medium. In instances where the dot position is to be blank, the unused drop or drops are deflected to an ink gutter from whence they can be returned to the ink supply system. Both electrostatic and magnetic deflection systems are employed. Also electrostatic and magnetic deflection hybrid systems are known, as illustrated in an IBM Technical Disclosure Bulletin, September 1975, page 1115.
Magnetic selection of wanted and unwanted drops is limited in usefulness because of the relatively slow field switching rates and power dissipation problems. Similarly, electrostatic deflection involves charge interaction problems.